//#define  _CRT_SECURE_NO_WARNINGS
//#include <iostream>
//#include <cmath>
//using namespace std;
//
////int main()
////{
////	int n;
////	cin >> n;
////	int ret = 0;
////	for (int i = 1; i <= n; i++)
////	{
////		ret += i;
////	}
////	ret++;
////	cout << ret;
////} 
//int main()
//{
//	int n;
//	cin >> n;
//
//	cout << pow(2, n - 1);
//}